1. Field of the Invention
The present invention relates to sheet material dispensers in general. More particularly, the present invention relates to sheet material dispensers capable of dispensing individual sheets from a roll of sheet material. The individual sheets are defined by rows of perforations in the sheet material.
2. Background of the Invention
Sheet material dispensers are designed to dispense individual sheet material from various sources including folded sheet material and rolled sheet material. Each type of sheet material source requires a different means of dispensing the sheet material. As a result, each source has unique problems in controlling how much sheet material is dispensed, and how quickly more sheet material is made available.
Folded sheet material dispensers contain separate sheets of folded sheet material that are dispensed through an opening. When a user removes a single sheet from the opening, another individual sheet is instantly made available. As a result, several sheets can be removed at once. Because the sheets are so readily available, there is no real limit to how many sheets can be removed by the user. Therefore, folded sheet material dispensers must by constantly checked to make sure they are full.
One common type of sheet dispensers dispenses sheet material wound on rolls. These dispensers have several different means of dispensing paper. The sheets can be removed by either pulling on a free end of a sheet or actuating a lever to advance the sheet. These dispensers usually have a cutter to sever the individual sheet from the source of sheet material. The cutter can be arranged adjacent to the opening, in which case the user removing the sheet must force the sheet against the cutter. Otherwise, the cutter is formed as part of a cutting drum mechanism.
The most simple dispensers rely on the user to pull on a free end of sheet material, thereby causing the sheet material to be dispensed. The amount of force necessary to dispense the sheet material depends in part on the location of the cutter. It takes more force to remove an individual sheet where the cutter is part of a cutting drum mechanism as compared to when the cutter is located adjacent to the opening. When the cutter is part of the cutting drum mechanism, it is the rotational momentum of the cutting drum that severs the individual sheet from the sheet material roll. To obtain the required amount of rotational momentum, the user has to apply more force than simply pulling the sheet material against the cutter.
Due to relatively recent advances in paper making technology that permit relatively easy formation of perforations in sheet material, there are now a number of dispensers capable of dispensing sheet material having spaced rows of preformed perforations. Such perforations weaken the sheet material, making it easier to separate an individual sheet from the remainder of sheet material. Some conventional dispensers for this type of sheet material have drawbacks and disadvantages. For example, these dispensers are designed so that after an individual sheet is dispensed, a sufficient length (tail end) of sheet material normally remains extended from the dispensing outlet to be grasped by the next user. Sometimes, however, when the sheet material tears along a perforation line positioned inside the dispenser, there is little or no exposed length of sheet material that can be grasped. In some cases, this requires the next user to actuate a manual lever or crank that could spread germs or other contaminants from one user to another.
The present inventors have proposed to improve sheet material dispensing by providing a sheet material dispenser with perforation detecting capability, for example. Such detection, however, is challenging because the translucence of the some types of sheet material may provide false indications of perforations.
In light of the foregoing, there is a need in the art for an improved dispenser and method for dispensing sheet material.
Accordingly, the present invention is directed to a dispenser for dispensing sheet material and a method of dispensing that substantially obviate one or more limitations of the related art. In one advantageous aspect, the present invention facilitates dispensing of individual sheets from a source of sheet material having a plurality of spaced perforations.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a dispenser for dispensing sheet material including a plurality of spaced perforations. The dispenser includes a housing defining an interior for accommodating a source of the sheet material, and an outlet through which the sheet material is dispensed. A perforation sensor is configured to sense perforations in the sheet material, and this perforation sensor is disposed in the interior of the housing. The perforation sensor includes at least one light receptor, and at least a portion of the perforation sensor is positioned in the housing to contact sheet material traveling from the source to the outlet, thereby spreading perforations in the sheet material.
In another aspect, the portion of the perforation sensor is a light emitter configured to emit light capable of being detected by the light receptor. The light emitter and the light receptor are spaced apart from one another such that the sheet material can be positioned between the light emitter and light receptor. This allows light to pass from the emitter to the receptor via the perforations, where the spreading of the perforations increases the amount of light passing through the perforations.
In yet another aspect, the sheet material is dispensed in a first direction. The perforation sensor is located in the housing such that the portion of the perforation sensor contacts the approximate middle of the sheet material in a second direction perpendicular to said first direction.
In another aspect, the dispenser further includes at least one rotatable roller in the housing. At least a portion of the sheet material is in contact with the roller when the sheet material travels from the source to the outlet.
In a further aspect, the roller includes at least two spaced sections and the portion of the perforation sensor is positioned between the roller sections to contact sheet material on the rollers.
In an additional aspect, the dispenser includes a brake configured to brake rotational movement of the roller and a controller for controlling the brake. The controller is in electrical communication with the perforation sensor.
In yet another aspect, the brake includes a detent member coupled to the roller, and a solenoid mounted to the housing. The detent member has a plurality of detents provided thereon, the solenoid has a plunger configured to selectively engage a respective one of the detents.
In another aspect, there are two light receptors. The perforation sensor also includes a differential trans-impedance amplifier for detecting light incident upon the two light receptors.
In a further aspect the differential trans-impedance amplifier is configured as a balanced bridge for amplifying the difference in intensity of light detected by the two light receptors.
In an additional aspect the differential trans-impedance amplifier includes a first operational amplifier, a second operational amplifier, a feed back resistor, a scaling resistor, and a gain resistor. The first operational amplifier has an inverting input node, a non-inverting input node, and an output node. The second operational amplifier has an inverting input node, a non-inverting input node, and an output node. The feedback resistor has a first end and a second end, wherein the first end is electrically coupled to the inverting input node of the first operational amplifier. The scaling resistor has a first end and a second end. The first end of the scaling resistor is electrically coupled to the second end of the feedback resistor and the second end of the scaling resistor is electrically coupled to the inverting input node of the second operational amplifier. The gain resistor has a first end and a second end. The first end of the gain resistor is electrically coupled to the inverting input node of the second operational amplifier and the second end of the gain resistor is electrically coupled to the output node of the second operational amplifier.
In another aspect of the present invention, the dispenser includes a housing defining an interior for accommodating a source of the sheet material, and an outlet through which the sheet material is dispensed. A perforation sensor is configured to sense perforations in the sheet material. The perforation sensor is disposed in the interior of the housing. The perforation sensor includes a pair of light receptors which are aligned in substantially the direction of sheet material travel from the source to the outlet. The pair of light receptors are arranged such that one of the receptors receives light passing through one of the perforations before the other receptor.
In another aspect, the perforation sensor includes a light emitter spaced from the pair of receptors such that the sheet material passes between the light emitter and the pair of light receptors during travel of the sheet material to the outlet.
In yet another aspect, the sheet material includes lines of the perforations defining individual sheets. The receptors are arranged such that the receptors are aligned along an axis substantially perpendicular to lines of perforations on the sheet material traveling adjacent to the receptors.
In another aspect, the dispenser includes a controller. The controller compares the amount of light detected by each light receptor.
In yet another aspect of the invention, the dispenser includes a housing defining an interior for accommodating a source of the sheet material, and an outlet through which the sheet material is dispensed. A perforation sensor is disposed in the interior of the housing. The perforation sensor is configured to sense perforations in the sheet material and includes at least one light receptor and a light emitter. The light receptor and the light emitter are spaced apart from one another such that the sheet material travels between the light emitter and light receptor. This allows light to pass from the emitter to the receptor via the perforations.
In another aspect, the dispenser includes a first rotatable roller in the housing. The first roller includes at least two spaced roller sections, where at least a portion of the sheet material is in contact with the first roller when the sheet material travels from the source to the outlet. Either the light receptor or the light emitter is positioned between the roller sections.
In an additional aspect, the dispenser includes a second rotatable roller in the housing, the first and second rollers defining a nip for the sheet material.
In another aspect, the dispenser includes a controller in said housing. The controller selectively activates the perforation sensor.
In an additional aspect, the dispenser further includes at least one rotatable roller in the housing. At least a portion of the sheet material is in contact with the roller when the sheet material travels from the source to the outlet. A rotation monitor is configured to monitor rotation of the roller. The controller is in electrical communication with the rotation monitor and activates the perforation sensor when the monitor detects a first predetermined amount of rotation of the roller.
In an even further aspect, the dispenser includes a brake configured to brake rotational movement of the roller, where the controller selectively activates the brake.
In an additional aspect, the controller is configured to activate the brake when the perforation sensor senses a perforation in the sheet material.
In another aspect of the present invention, the dispenser includes a housing defining an interior for accommodating a source of the sheet material, and an outlet through which the sheet material is dispensed. At least one rotatable roller in the housing, and at least a portion of the sheet material being in contact with the first roller when the sheet material travels from the source to the outlet. The dispenser also includes a rotation monitor configured to monitor the amount of rotation of the roller to thereby determine the amount of sheet material traveling downstream from the roller.
In yet another aspect, the present invention includes a method of dispensing sheet material. The method includes providing a dispenser containing a source of sheet material including a plurality of spaced perforations. The dispenser includes a perforation sensor including at least one light receptor and a light emitter, at least one rotatable roller, a brake configured to selectively brake rotation of the roller, and an outlet for dispensing sheet material. The method includes passing sheet material from the source to the outlet wherein the sheet material contacts the roller and the roller rotates. The sheet material passes between the light receptor and the light emitter. The method includes detecting a perforation in the sheet material by sensing an increased amount of light reaching said light receptor from said light emitter. The method includes activating the brake to cause tension in the sheet material when an end portion of the sheet material is pulled.
In another aspect, the method includes monitoring the amount of rotation of the roller and activating the perforation sensor when the roller rotates a first predetermined amount.
In an additional aspect, the method includes activating the brake when the perforation sensor detects a perforation and the roller rotates a second predetermined amount.
In another aspect, the brake includes a detent member and a solenoid having an arm configured to selectively engage the detent member when the solenoid is activated. The method includes activating the solenoid.
In yet another aspect, the present invention includes a method of dispensing sheet material. The method includes providing a dispenser for containing a source of sheet material including a plurality of spaced perforations. The dispenser includes at least one rotatable roller, a rotation monitor configured to monitor the amount of rotation of the roller to thereby determine the amount of sheet material traveling downstream from the roller, a brake configured to selectively brake rotation of the roller, and an outlet for dispensing sheet material. The method includes passing sheet material from the source to the outlet, wherein the sheet material contacts the roller and the roller rotates. The method includes monitoring the amount of rotation of the roller to thereby determine the amount of sheet material dispensed. The method includes activating the brake when a predetermined amount of sheet material is dispensed, said activation causing tension in the sheet material when an end portion of the sheet material is pulled.
In another aspect, the dispenser further includes a perforation sensor including at least one light receptor and a light emitter. The method further includes detecting an initial rotation of the roller. The perforation sensor is activated when the roller rotates a first predetermined amount of rotation. The brake is activated when at least one of the perforation sensor detects a perforation and the roller rotates a second predetermined amount.
In yet another aspect, the present invention includes a method of dispensing individual sheets from a dispenser containing a source of sheet material having a plurality of spaced perforations. The dispenser includes at least one rotatable roller, a rotation monitor configured to monitor the amount of rotation of the roller to thereby determine the amount of sheet material traveling downstream from the roller, a perforation sensor for sensing perforations in the sheet material, and an outlet for dispensing sheet material. The method includes detecting the amount of rotation of the roller, and sensing a perforation in the sheet material. In response to detection of said perforation, the method includes stopping the advancing of the sheet material when the roller rotates a first predetermined amount.
In a further aspect, the method includes detecting an initial rotation of the roller.
In an additional aspect, the method includes activating the perforation sensor after a second predetermined amount of rotation of the roller.
In yet another aspect, in a response to no perforation being detected when the roller rotates a third predetermined amount, the method includes stopping the advancing of the sheet material.
In an additional aspect, the dispenser includes a brake configured to selectively brake rotation of the roller, and wherein the stopping of sheet material advancing includes activating the brake.
Additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.